Dual clutch transmissions (DCTs) have an automatic direct-shifting gearbox (DSG) with an integrated dual clutch. These transmissions are designed to deliver good driver acceptance in combination with better fuel economy than step type automatic transmissions. Coordination of the manual transmission gears is achieved through the use of dual wet clutches. As a result, performance requirements of fluids for such transmissions require elements critical for both manual transmissions (such as extreme pressure and synchronization demands) and automatic transmissions (such as steel-on-friction material performance and friction durability demands). A variation of this transmission system is one where the dual wet clutches (clutch and hydraulic system) and the direct-shifting gearbox have separate oil cycles. In such a system, the wet clutches (clutch and hydraulic system) use a “clutch-only” fluid with different performance requirements than those described above.
The presently disclosed embodiments provide fluids that provide enhanced performance in the wet clutches and meet the unique demands of this “clutch-only” fluid.